Abstract
Diploid populations of Aegilops mutica and Aegilops speltoides containing B chromosomes have been used as male parents in crosses with aneuploid genotypes of Triticum aestivum to investigate the effect of B chromosomes on meiotic homologous and homoeologous chromosome pairing. F1 hybrids of T. aestivum/Ae. mutica and T. aestivum/Ae. speltoides segregated into four classes with regard to the degree of meiotic chromosome pairing, irrespective of the presence of B chromosomes. The B chromosomes do not introduce factors altering the level of pairing other than that due to the natural allelic and gene variation occurring in the diploids. Similarly no reduction in pairing of homologous chromosomes was observed in genotypes in which pairs of homologues co-existed with B chromosomes. However, a significant drop in chiasma frequency was observed in F1 hybrids of T. aestivum × Ae. mutica with B chromosomes and T. aestivum × Ae. mutica nullisomic for wheat chromosome 5D with B chromosomes, in temperature regimes of 12° C. No asynapsis occurred in similar hybrids in the absence of Mutica B chromosomes at low temperatures. The low-temperature sensitive phase lies early in the pre-meiotic interphase. In this instance the Mutica B chromosomes are interacting with specific gene loci of the A chromosomes. Synaptic pairing has been observed between A and B chromosomes in Ae. mutica. A high frequency of pollen mother cells with twice the number of chromosomes was observed in hybrids in the presence of Mutica B chromosomes due to failure of spindle formation at the last pre-meiotic mitosis. Meiotic spindle irregularities occurred in hybrids containing Speltoides B chromosomes. Hybrids of Ae. speltoides + B's X Ae. mutica + B's displayed the mitotic and meiotic spindle abnormalities introduced by the presence of the B chromosomes of each parent.
Similar content being viewed by others
References
Battaglia, E.: Cytogenetics of B-chromosomes. Caryologia (Pirenze) 17, 245–299 (1964).
Bayliss, M. W., Riley, R.: Evidence of pre-meiotic control of chromosome pairing in Triticum aestivum. Genet. Res. (Cam.) (in press 1972).
Dover, G. A., Riley, R.: Variation at two loci affecting homoeologous meiotic chromosome pairing in Triticum aestivum x Aegilops mutica hybrids. Nature (Lond.) New Biol. 235, 61–62 (1972).
Evans, G. M., Macefield, A. J.: The suppression of homoeologous pairing by B-chromosomes in a Lolium species hybrid. Nature (Lond.) New Biol. 236, 110–111 (1972).
Feldman, M.: The regulation of chromosome pairing in inter-varietal, inter-specific and inter-generic hybrids of common wheat. Eu. Wheat Aneup. Co-op. 3, 2–4 (1971).
Gibson, I., Hewitt, G.: Isolation of DNA from B-chromosomes in grasshoppers. Nature (Lond.) 225, 67–68 (1970).
Lewis, H.: Quantitative variation in wild genotypes of Clarkia. I.U.B.S. Symp. gen. Popul. Structure, Pavia 1953, 114–125 (1953).
Mendelson, D.: Behaviour and transmission of supernumary chromosomes in Aegilops speltoides. M. Sc. thesis, Hebrew Univ. Jerusalem (1971).
Mochizuki, A.: B-chromosomes in Aegilops mutica Boiss. Wheat Inf. Serv. 5, 9–11 (1957).
Mochizuki, A.: Further studies on the effect of accessory chromosomes on chromosome pairing. Jap. J. Genet. 39, 356–362 (1964).
Riley, R.: The genetic regulation of meiotic behaviour in wheat and its relatives. Proc. 2nd Int Wheat Genet Symp. Lund 1963.
Hereditas (Lund), Suppl. 2 (1966a). Riley, R.: Genotype-environmental interaction affecting chiasma frequency in Triticum aestivum. Chromosomes today (C. D. Darlington and K. R. Lewis, eds.), 1, 57–65 (1966b).
Riley, R., Kimber, G., Chapman, V.: The origin of the genetic control of the diploid-like meiotic behaviour of polyploid wheat. J. Hered. 52, 22–26 (1961).
Walker, P. M. B.: Origin of satellite DNA. Nature (Lond) 229, 306–308 (1971).
Yunis, J. J., Yasmineh, W. G.: Heterochromatin, satellite DNA and cell function. Science 174, 1200–1209 (1971).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Vardi, A., Dover, G.A. The effect of B chromosomes on meiotic and pre-meiotic spindles and chromosome pairing in Triticum/Aegilops hybrids. Chromosoma 38, 367–385 (1972). https://doi.org/10.1007/BF00320157
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00320157